1. Field
One or more embodiments herein relate to a rechargeable lithium battery.
2. Description of the Related Art
A rechargeable lithium battery is used to power many types of electronic devices because of its performance characteristics. For example, a rechargeable lithium battery may have a discharge voltage (and thus an energy density) greater than other batteries, e.g., ones using an aqueous alkaline solution.
Structurally, a rechargeable lithium battery may have a separator between positive and negative electrodes and an electrolyte. The electrodes include a current collector and an active material layer. The positive electrode may be made from oxides of lithium and transition metal having a structure into which lithium ions are capable of intercalating. Examples include LiCoO2, LiMn2O4, LiNi1-xCoxO2 (0<x<1).
The negative electrode may be made from carbon-based materials, e.g., artificial graphite, natural graphite, or hard carbon capable of intercalating and deintercalating lithium ions However, because a carbon-based negative active material causes non-reversible capacity, lithium corresponding to the non-reversible capacity of the negative electrode is insufficient in the positive electrode. As a result, the potential (Li/Li+) of the positive electrode may increase to deteriorate the lifecycle of the battery.
This effect may occur because the initial discharge of an initial charge of the negative electrode is not good, e.g., initial discharge efficiency is not good. Moreover, generation of a non-reversible capacity of the negative electrode and deterioration of discharge efficiency may intensify for greater thicknesses of the active material layer and when there is a high active mass.
Various methods haven been proposed in an attempt to increase the initial discharge efficiency of the negative electrode. One method involves pressurizing and transferring a stabilized lithium metal powder or a lithium metal carrier film prepared by coating the stabilized lithium metal powder on a releasing film.